
June 16, 1923] 
NA TURE 
831 

can be made into slabs and pressed into crucibles, if ) taining a high percentage of the latter. A mixture 
care is taken in working it. 
DvuBLIN. 
- Royal Irish Academy, May 28.—Prof. Sydney 
Young, president, in the chair—J. J. Drumm: The 
constitution of catechin, Part I. Benzopyranol salts 
are prepared from catechin of a type closely allied to 
the anthocyanidins. Von Kostanecki’s coumarane 
formula for catechin is no longer tenable; A. G. 
Perkin’s chromane formula with slight modifications 
is again put forward. 
Royal Dublin Society, May 29.—Prof. J. A. Scott 
in the chair.—Rev. H. C. Browne: A simple from of 
pe eeeanlic depth chart. The chart consists of 
our concurrent lines, and may conveniently be 
drawn on squared paper. A straight edge laid any- 
where across these lines intersects them in points 
which give respectively the stop diameter, the nearest 
distance in focus, the distance to be sharply focussed 
on, and the furthest distance in focus. The readings 
are all direct, reciprocals being avoided. Three 
sample charts were described, one suited for general 
work, a second especially adapted for the photography 
of small objects at short distances and on an enlarged 
scale up to 12 or more diameters, and a third intended 
for carrying in a photographic note-book, which, 
though only 34 in. x 24 in. in size, gives clear readings 
for distances up to 60 feet, and stop diameters up to 
1-5 inches.—T. G. Mason: Ligneous zonation and 
die-back in the lime (Citrus medica, var. acida) in the 
West Indies. Tangential bands of parenchyma are 
distributed in the wood in both normal lime tree 
and in specimens affected with ‘“‘ die-back’’; they 
originate during periods of relatively great aridity. 
The wood from trees affected with die-back exhibits 
considerable irregularity in the distribution of the 
parenchyma bands, and the sections suggest that the 
cambium had been exposed to sudden checks in its 
activity. Rapid and repeated desiccation of the 
meristems may be an important factor in causing 
die-back of the lime.—L. B. Smyth: Ona problematic 
structure in the Oldhamia Rocks of Bray Head. 
These rocks consist of scattered tabular bodies 0-3 
mm. in thickness, with rectilinear outlines and of 
variable size (average, 1-3 mm. diameter) and shape, 
lying on a bedding plane of chlorite-sericite shale. 
Their composition differs from that of the shale only 
by the greater proportion of chlorite. A considerable 
number of the bodies are lozenge-shaped. They may 
be crushed pseudomorphs of crystals. 
ParRIs. 
Academy of Sciences, May 22.—M. Albin Haller in 
the chair. The president announced the death of 
M. de Freycinet, Free Academician.—A. Vayssiére : 
The characters suitable for classifying the gasteropods 
of the family of the Cypreidee. These have hitherto 
been mainly classified according to the character of 
the shell and this is shown to be insufficient.—M. 
Pélissier: An account of the formation of a new 
volcanic island south ot Poulo-Cécir de Mer. Plans 
of the island and crater, together with a chart show- 
ing soundings round the new island are given.—Paul 
Lévy: <A _ functional 
derivation of non-integral order.—P. Zervos: Some 
transformations of partial differential equations.— 
A. Guillet: The rapid and precise measurement of 
the frequency of rotation of the shaft of a motor by 
the stroboscopic method. A description of the 
construction and use of an improved form of stretched 
wire stroboscope.—M. Dumanois: The utilisation (in 
a motor) of a mixture of lamp oil and alcohol con- 
NO. 2798, VOL. 111] 
state of gases.—E. Brylinski: 
maintained electromagnetic waves along an iron wire. 
operation generalising the’ 

of alcohol (7o per cent.) and kerosene (30 per cent.) 
“was successfully used to replace petrol in a motor 
car: the car was run on this mixture (after suitably 
-modifying the carburettor) from Paris to Toulouse, 
450 miles, without trouble-—Jean Durand: Contribu- 
tion to the study of methods of testing foundry 
iron.—Albert Bazin: The hovering flight of birds : 
flights without motor in undulating winds.—M. 
Auric: Demonstration of Stefan’s law.—A. Leduc: 
The loop of J. Thomson and the new equation of 
The propagation of 
Remarks on a recent communication of M. G. Laville 
on the same subject.—J. Rossignol: Researches on 
the cathode phosphorescence of the ruby. An 
examination of the influence of the velocity of the 
stimulating cathodic electrons on the law of decrease 
of phosphorescence of the ruby with time. Synthetic 
rubies were employed, with percentages of chromic 
oxide varying between o-1 per cent: and Io per cent. 
Curves for one ruby are given, showing the relation 
between the intensity of phosphoresence, voltage of 
the poles of the cathode tube, and fall of intensity 
with the time.—Mlle. Iréne Curie: An arrangement 
for measuring strong ionisations due to the a-rays. 
The principle of the method consists in utilising for 
the ionisation current only a fraction of the a-rays. 
This portion is allowed to escape through sectors in a 
brass cover and the ratio of reduction, which can be 
varied, may be as high as yss50-——M. Volmar: The 
action of light on the tartar emetics. Tartrates of 
the type CO,H . CH(OH) . CHO(RO) . CO,K, in which 
R may be antimony, arsenic or bismuth, are decom- 
posed by ultra violet light, gas being evolved (carbon 
dioxide, carbon monoxide and hydrogen and hydro- 
carbons in the case of antimony), and metal 
deposited. Double tartrates of copper and of iron 
are also changed by exposure to light of short 
wave length.—Albert Noyes, jun.: The photo- 
chemical decomposition of solid bodies.—A. Bigot: 
Kaolins, clays, etc. Colloidal plasticity. Experi- 
ments on baking clay briquettes prepared in different 
ways, compression of dry powder, compression of 
slightly moistened powder, reduction to plastic state 
with water. The colloids play an important part in 
the results of firing ceramic materials —F. Zambonini : 
Thorium molybdate, Th(Mo O,),. An account of the 
mode of preparation, crystal form and molecular 
volume of thorium molybdate.—Pierre Jolibois and 
Pierre Lefebvre: Baking of plaster of Paris and 
its preservation in moist air. Plaster of Paris which 
has been dehydrated at temperatures between 150° 
and 300° C. rapidly absorbs water vapour from 
saturated air: if the dehydration temperature has 
been above 400° C. the rate of absorption of water 
vapour is very slow.—F. Diénert and F. Wanden- 
bulcke: The estimation of silica in water. The 
method suggested is based on the colour developed 
by the addition of ammonium molybdate and dilute 
sulphuric acid, utilising a standard solution of picric 
acid as a colour standard.—Max and Michel Polo- 
novski: Etheserolene.—Ch. Mauguin: The arrange- 
ment of the atoms in crystals of cinnabar. The results 
of an X-ray study of cinnabar crystals.—Mlle. 
Gertrude Weber: The limit between the Danian and 
the Maestrichtian in the Crimea.—L. Vegard: The 
constitution of the upper layers of the atmosphere. 
In a previous communication on the spectrum of the 
aurora borealis it has been shown that nitrogen is the 
dominating element at the upper limit of the atmo- 
sphere. It is probable that the nitrogen is solidified 
in the form of small crystals, and that this nitrogen 
dust is charged electrically by the photoelectric effect 
of the solar radiation—Henri Coupin: Remarks on 
